string-pad.js 1.3 KB

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  1. // https://github.com/tc39/proposal-string-pad-start-end
  2. var toLength = require('../internals/to-length');
  3. var toString = require('../internals/to-string');
  4. var repeat = require('../internals/string-repeat');
  5. var requireObjectCoercible = require('../internals/require-object-coercible');
  6. var ceil = Math.ceil;
  7. // `String.prototype.{ padStart, padEnd }` methods implementation
  8. var createMethod = function (IS_END) {
  9. return function ($this, maxLength, fillString) {
  10. var S = toString(requireObjectCoercible($this));
  11. var stringLength = S.length;
  12. var fillStr = fillString === undefined ? ' ' : toString(fillString);
  13. var intMaxLength = toLength(maxLength);
  14. var fillLen, stringFiller;
  15. if (intMaxLength <= stringLength || fillStr == '') return S;
  16. fillLen = intMaxLength - stringLength;
  17. stringFiller = repeat.call(fillStr, ceil(fillLen / fillStr.length));
  18. if (stringFiller.length > fillLen) stringFiller = stringFiller.slice(0, fillLen);
  19. return IS_END ? S + stringFiller : stringFiller + S;
  20. };
  21. };
  22. module.exports = {
  23. // `String.prototype.padStart` method
  24. // https://tc39.es/ecma262/#sec-string.prototype.padstart
  25. start: createMethod(false),
  26. // `String.prototype.padEnd` method
  27. // https://tc39.es/ecma262/#sec-string.prototype.padend
  28. end: createMethod(true)
  29. };